public void ConcatThrowsArgumentNullExceptionWhenTargetSequenceIsNull() { IAsyncEnumerable <int> source = Integer.RandomSequence(16).ToAsyncEnumerable(), target = null; source.ShouldNotBeNull(); target.ShouldBeNull(); source.ConcatAsync(target) .ConsumeAsync() .ShouldThrow <ArgumentNullException>(); }